Apparatus for simultaneously recording and reproducing data to and from a recording medium

ABSTRACT

A data compressing unit compresses information data inputted from an input unit. An input buffer unit temporarily stores the compressed data obtained by the data compressing unit. A recording/reproducing unit records the compressed data read out from the input buffer unit onto a recording medium, and reproduces the compressed data recorded on the recording medium. An output buffer unit temporarily stores the compressed data reproduced by the recording/reproducing unit. A data expanding unit expands the compressed data read out from the output buffer unit. An output unit outputs data expanded by the expanding unit. For this reason, when one set or cluster of information data is assumed to be information data file, it is possible to reproduce, without necessity of interruption of recording of the entirety of the information data file, the portion recorded earlier, e.g., by several minutes to several tens minutes within the same information data file.

TECHNICAL FIELD

This invention relates to an information data recording/reproducingapparatus adapted for recording information data from an informationdata input unit to reproduce the recorded information data to outputreproduced data to an information data output unit, and an informationdata processing system provided with such information datarecording/reproducing unit.

BACKGROUND ART

Hitherto, in supplying, upon occasion, a plurality of information datarecorded by a plurality of input units to plural viewers (viewing andlistening persons) through a plurality of output units, reproducingunits were required every plural viewers.

If information data is, e.g., video data, video tape recorders 54 wererequired as shown in FIG. 1 for plural viewers. For example, videosignals obtained through a satellite antenna 51 were recorded onto avideo tape 53 by means of a video tape recorder 52 for input to supply,upon occasion, such video tape 53 on which those video signals arerecorded to viewers by means of video tape recorders 54 for outputdedicated to the viewers. Moreover, the case where, e.g., video signalsimaged (taken) by a camera 55 for studio are recorded by means of avideo tape recorder 56 for input to provide, upon occasion, those videosignals, and/or the case where video signals imaged (taken) by using aportable compact camera integrated type video tape recorder 57 atoutdoor place are supplied upon occasion are also similar to the above.

Meanwhile, as shown in FIG. 1, in the video data recording/reproducingsystem in which input video tape recorders 52 and 56, and output videotape recorders 54 are used to send out recorded video signals toviewers, as occasion demands, various problems were arisen resultingfrom the fact that the recording medium is video tape 53.

Initially, in the case where a set (cluster or bundle) of video signalsare assumed to be called video data file, when such one video data fileis being recorded, it was difficult to reproduce, without interruptingrecording of the entirety of the video data file, the portion recordedearlier by several ten minutes within the video data file.

Moreover, it was impossible to supply one video data file to pluralviewers under the state shifted by small time differences. To realizethis, it was necessary to prepare plural video tapes on whichcorresponding video data file is copied and recorded.

Further, it was impossible to reproduce a plurality of video data fileswithin the same video tape without interruption in an arbitrary orderthat viewers desire. To realize this, it was necessary to prepare avideo tape on which plural video data files are recorded in an arbitraryorder that viewers desire.

Further, it was impossible to reproduce, without interruption, pluralvideo data files with respect to different video tapes.

Further, in the above-mentioned video data recording system, video datafrom respective dedicated input units are recorded by a single recordingunit and is reproduced by a single reproducing unit for a single viewer.Recording/reproduction operations of plural channels were not carriedout by a single recording/reproducing unit. For this reason, first ofall, there resulted high cost in construction of the system.

This invention has been made in view of the above-described actualcircumstances, and its object is to provide an information datarecording/reproducing apparatus and an information data processingsystem which are capable of reproducing the portion recorded earlier by,e.g., several minutes to several ten minutes within the same data filein the state where interruption of recording of the entirety of the datafile is caused to be unnecessary.

Another object of this invention is to provide an information datarecording/reproducing apparatus and an information data processingsystem which can supply the same data file to plural viewers in thestate shifted by arbitrary time differences.

A further object of this invention is to provide an information datarecording/reproducing apparatus and an information data processingsystem which can make time-division recording/reproduction of pluralchannels.

DISCLOSURE OF THE INVENTION

An information data recording/reproducing apparatus according to thisinvention comprises: input means adapted so that information data arecontinuously inputted thereto; data compressing means for compressinginformation data inputted from the input means to obtain compresseddata; input buffer means for temporarily storing the compressed dataobtained by the data compressing means; recording/reproducing means forrecording the compressed data read out from the input buffer means ontoa recording medium, and reproducing the compressed data recorded on therecording medium; output buffer means for temporarily storing thecompressed data reproduced by the recording/reproducing means; dataexpanding means for expanding the compressed data read out from theoutput buffer means; output means for outputting data expanded by theexpanding means; and control means for controlling read-out timing ofthe compressed data from the input buffer means, read-out timing of thecompressed data from the output buffer means, and operations ofrecording and reproduction of the compressed data by therecording/reproducing means so that recording onto the recording mediumof the compressed data and reproduction from the recording medium by therecording/reproducing means are carried out in a time divisional manner,and the information data are continuously outputted from the outputmeans.

The information data recording/reproducing apparatus is such that therecording/reproducing means is composed of a plurality ofrecording/reproducing circuits for recording/reproducing the compresseddata, and includes dividing means for dividing the compressed datacompressed by the compressing means in correspondence with the pluralityof recording/reproducing circuits.

Moreover, the information data recording/reproducing apparatus furtherincludes error correction code adding means for adding error correctioncode to the compressed data thus to allow at least one of the pluralityof recording/reproducing circuits to record/reproduce only the errorcorrection code.

Further, the input means of the information data recording/reproducingapparatus is composed of a plurality of interface circuits, the datacompressing means is composed of a plurality of compressing circuits forrespectively compressing the information data inputted through theplurality of interface circuits; the input buffer means is composed of aplurality of input buffer circuits for respectively storing thecompressed data compressed at the plurality of compressing circuits; therecording/reproducing means is composed of a plurality ofrecording/reproducing circuits for recording/reproducing the compresseddata; and the output buffer means is composed of a plurality of outputbuffer circuits for respectively temporarily storing the compressed datareproduced at the plurality of recording/reproducing circuits; and theapparatus further includes distribution gathering means connectedbetween the plurality of input buffer circuits and the plurality ofoutput buffer circuits and the plurality of recording/reproducingcircuits, operative to divide the compressed data supplied from one ofthe plurality of input buffer circuits to supply them to the pluralityof recording/reproducing circuits, and to gather compressed datarespectively reproduced from the plurality of recording/reproducingcircuits to supply the gathered data to one of the plurality of outputbuffer circuits.

Further, the recording/reproducing circuit of the information datarecording/reproducing apparatus is a disc unit adapted for recording thecompressed data onto a disc shaped recording medium, and reproducing thecompressed data from the disc-shaped recording medium.

In addition, the information data recording/reproducing apparatus may beused under the state where the input means and the output means, thedata compressing means and the data expanding means, and the inputbuffer means and the output buffer means are respectively selectivelyreplaced each other.

An information data processing system according to this inventioncomprises: at least one information data input unit for generatinginformation data; at least one information data output unit; and aninformation data recording/reproducing unit including data compressingmeans for compressing the information data supplied from the informationdata input unit to obtain compressed data, input buffer means fortemporarily storing the compressed data obtained by the data compressingmeans, recording/reproducing means for recording the compressed dataread out from the input buffer means onto a recording medium, andreproducing the compressed data recorded on the recording medium, outputbuffer means for temporarily storing the compressed data reproduced bythe recording/reproducing means, data expanding means for expanding thecompressed data read out from the output buffer means, and control meansfor controlling read-out timing of the compressed data from the inputbuffer means, read-out timing of the compressed data from the outputbuffer, operations of recording and reproduction of the compressed databy the recording/reproducing means so that recording onto the recordingmedium of the compressed data and reproduction from the recording mediumby the recording/reproducing means are carried out in a time-divisionalmanner, and the information data are continuously outputted with respectto the output unit.

Moreover, another information data processing system according to thisinvention comprises: at least one information data input unit forgenerating information data; a data compressing unit for compressing theinformation data supplied from the information data input unit to obtaincompressed data; an information data recording/reproducing unitcomprising input buffer means for temporarily storing the compresseddata obtained by the data compressing unit, recording/reproducing meansfor recording the compressed data read out from the input buffer meansonto a recording medium and reproducing the compressed data recorded onthe recording/reproducing means, output buffer means for temporarilystoring the compressed data reproduced by the recording/reproducingmeans, and control means for controlling read-out timing of thecompressed data from the input buffer means, read-out timing of thecompressed data from the output buffer and operations of recording andreproduction of the compressed data by the recording/reproducing meansso that recording onto the recording medium of the compressed data andreproduction from the recording medium by the recording/reproducingmeans are carried out in a time divisional manner, and the informationdata are continuously outputted with respect to at least one informationdata output unit described below through a data expanding unit describedbelow; the data expanding unit for expanding the compressed dataoutputted from the information data recording/reproducing unit; and theinformation data output unit for outputting data expanded by the dataexpanding unit.

The recording/reproducing means of the information datarecording/reproducing unit that the above-mentioned another informationdata processing system comprises is composed of a plurality ofrecording/reproducing circuits for recording/reproducing the compresseddata, and dividing means for dividing the compressed data incorrespondence with the plurality of recording/reproducing circuits.

Moreover, the information data recording/reproducing unit that theabove-mentioned another information data processing system comprisesfurther includes error correction code adding means for adding errorcorrection code to the compressed data, wherein at least one of theplurality of recording/reproducing circuits records/reproduces only theerror correction code.

Further, the data compressing unit that the above-mentioned anotherinformation data processing system comprises is composed of a pluralityof compression circuits; the input buffer means is composed of aplurality of input buffer circuits for respectively storing thecompressed data compressed by the plurality of compressing circuits; therecording/reproducing means is composed of a plurality ofrecording/reproducing circuits for recording/reproducing the compresseddata; and the output buffer means is composed of a plurality of outputbuffer circuits for respectively temporarily storing the compressed datareproduced at the plurality of recording/reproducing circuits, theinformation data recording/reproducing unit further includingdistributing/gathering means connected between the plurality of inputbuffer circuits and the plurality of output buffer circuits and theplurality of recording/reproducing circuits, and operative to divide thecompressed data supplied from one of the plurality of input buffercircuits to supply them to the plurality of recording/reproducingcircuits to gather compressed data respectively reproduced from theplurality of recording/reproducing circuits to supply the gathered datato one of the plurality of output buffer circuits.

Moreover, the input buffer means and the output buffer means of theinformation data recording/reproducing unit that the above-mentionedanother information data processing system comprises may be used underthe state where they are respectively selectively exchanged each other.

Further, the recording/reproducing means of the information datarecording/reproducing unit that the above-mentioned another informationdata processing system comprises includes plural number (except formultiple of 2 and 3) of recording/reproducing circuits, wherein thecontrol means controls the plurality of recording/reproducing circuitsso that they sequentially distribute video signals divided in frame orfield units to record them, and is operative so that in the case where ntimes speed of reproduction of the video signals is carried out, thecontrol means controls the plurality of recording/reproducing circuitsso as to reproduce in parallel video signals of n frame interval or nfield interval from the recording medium to transfer it to a buffermemory to obtain a video signal of frame or field of n times speed fromthe buffer memory.

The recording/reproducing circuit of the information datarecording/reproducing unit that the above-mentioned another informationdata processing system comprises is a disc unit adapted for recordingthe compressed data onto a disc-shaped recording medium to reproduce thecompressed data from the disc-shaped recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view for explaining a conventional video datarecording/reproducing system.

FIG. 2 is a view showing the state where a video datarecording/reproducing apparatus (unit) of a first embodiment of thisinvention is assembled into a video server system.

FIG. 3 is a view showing the configuration of the video datarecording/reproducing apparatus.

FIG. 4 is a timing chart at the time of recording operation of the videodata recording/reproducing apparatus.

FIG. 5 is a timing chart at the time of recording/reproducing operationof the video data recording/reproducing apparatus.

FIG. 6 is a view showing the configuration of a video data processingsystem which is a second embodiment of this invention.

FIG. 7 is a view showing the configuration of a video datarecording/reproducing apparatus (unit) used in the video data processingsystem shown in FIG. 6.

FIG. 8 is a view showing the configuration of a Video On Demand systemwhich is a third embodiment of this invention.

FIG. 9 is a view for explaining standard reproduction operation that theVideo On Demand system shown in FIG. 8 carries out.

FIG. 10 is a view for explaining double speed reproduction operationthat the Video On Demand system shown in FIG. 8 carries out.

FIG. 11 is a view for explaining triple speed reproduction operationthat the Video On Demand system shown in FIG. 8 carries out.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of an information data recording/reproducingapparatus and an information data processing system according to thisinvention will now be described with reference to the attached drawings.

First of all, an embodiment of an information data recording/reproducingapparatus according to this invention will be described below as a firstembodiment. This first embodiment is directed to a video datarecording/reproducing apparatus in which video data is handled asinformation data to record a set (cluster or bundle) of the video dataas video data file onto a disc-shaped recording medium such as hard discor magneto-optical disc to reproduce the video data file from thedisc-shaped recording medium. This video data recording/reproducingapparatus is used in a Video Server for providing the video data filefor a plurality of terminals.

Initially, the video data recording/reproducing apparatus which is thefirst embodiment assembled into the video server system will bedescribed with reference to FIG. 2. Video server system 11 comprises, asshown in FIG. 2, the video data recording/reproducing unit (apparatus) 5provided with recording/reproducing means for recording one channel orplural channels of video data supplied from a video data input unit suchas a receiving antenna i for communication satellite, a televisioncamera 2 and a video tape recorder 3, etc. to reproduce the recordedvideo data file into data of one channel or plural channels to output,in an arbitrary order, reproduced data to a video data output unit suchas a video tape recorder 3, a signal sending (transmitting) unit 4 and apicture monitor unit, etc., and to carry out, in a time divisionalmanner, recording and reproduction of the video data; a data transferunit 6 for serially transmitting video data from the video data inputunit to the video data recording/reproducing unit 5 and transferringvideo data file from the video data recording/reproducing unit 5 to thevideo data output unit; an edit control unit 7 for editing video datafile supplied through the data transfer unit 6; and a system controlunit 9 for controlling, through a control system network 8, operationsof the video tape recorder 3, the signal sending unit 4 and the videodata recording/reproducing unit 5. While signal sending unit 4, editcontrol unit 7, etc. are illustrated in such a manner that they existoutside the video server system 11, the video server system 11 isassumed to include these units in a broad sense as described above.

The video data recording/reproducing unit 5 comprises a disc drive 5aand a disc drive control section 5b. The disc drive control section 5bcontrols the operation of the disc drive 5a on the basis of a controlsignal supplied from the system control unit 9.

The data transfer unit 6 comprises a SDI (Serial Digital Interface)switching section 6a, and a switching control section 6b. The switchingcontrol section 6b allows the SDI switching section 6a to convert thevideo data into serial data on the basis of a control signal suppliedfrom the system control unit 9.

The video tape recorder 3 which serves as both the video data input unitand the video data output unit comprises a video tape recorder bodysection 3a and a video tape recorder control section 3b. The video taperecorder control section 3a control the operation of the video taperecorder body section 3a on the basis of a control signal supplied fromthe system control unit 9.

Between the video data input unit, the video data output unit, videodata recording/reproducing unit 5, the data transfer unit 6 and the editcontrol unit 7, data transfer system networks 10 are provided as shown.The video data is transmitted through the data transfer system networks10. An output signal of the video server system 11 is outputted also toan external unit, e.g., a picture monitor unit through the data transfersystem network 10 from the signal sending-out (transmitting) unit 4.

Video data obtained from video tape recorder 3, satellite antenna 1 andtelevision camera 2 which serve as the video data input unit are oncerecorded at the video data recording/reproducing unit 5 through the datatransfer unit 6. At this time, between the video data input unit and thedata transfer unit 6, the video data is subjected to serial digitaltransmission as described above. This data transfer unit 6 connectsbetween arbitrary equipments by SDI switching section 6a.

As stated above, the data transfer unit 6 and the video datarecording/reproducing unit 5 which constitute video server system 11 setconnection between equipments or recording place on the basis of controlcommand (instruction) supplied from the system control unit 9 throughthe control system network 8 to record video data supplied through thedata transfer system network 10 from the input data unit. As the controlsystem network 8, computer network such as network of medium scale usingcoaxial cable or large scale network, etc. using optical fiber may beutilized.

Video data recorded in the video data recording/reproducing unit 5 isread out from the disc drive 5a by control of the edit control unit 7,and is caused to undergo edit processing by the edit control unit 7. Thevideo data to which edit processing has been implemented at the editcontrol unit 7 is recorded onto the disc drive 5a for a second time. Inthis case, in addition to address data of video data which has not yetbeen caused to undergo edit processing, address data of video data afterundergone edit processing is held at the system control unit 9. Inaddition, in the case where edit processing is not particularlyrequired, and a portion necessary for sending-out is selected, sincesuch selective operation is required to have only address of thenecessary portion, such address data is held at the system control unit9.

Information relating to edit processing which has been executed inaccordance with control of the edit control unit 7 is held at the systemcontrol unit 9, and is sent also to a signal sending out unit 4 via thecontrol system network 8. Video data which has been read out from thevideo data recording/reproducing unit 5 is sent out to the externalthrough data transfer unit 6, signal sending unit 4 and data systemnetwork 10.

As described above, the video data recording/reproducing device 5 whichserves as the first embodiment is composed of disc unit 5a and discdrive control section 5b for controlling the disc drive 5a.

Initially, outline of the configuration of the video datarecording/reproducing unit 5 will be described with reference to FIG. 3.

This video data recording/reproducing unit 5 comprises disc drive 5aincluding a serial digital interface (hereinafter referred to as SDI/F)section 20 adapted so that the video data are continuously inputtedthereto, a compressing/expanding section 22 for compressing video datainputted from the SDI/F section 20 to obtain compressed video data andcarrying out expanding processing which will be described later, abuffer memory section 23 serving as input buffer means for temporarilystoring compressed video data obtained by the compressing/expandingsection 22, a disc unit section 28 for recording, onto, e.g., amagneto-optical disc, the compressed video data which has been read outfrom the buffer memory section 23 to reproduce the compressed video datarecorded on the magneto-optical disc, the buffer memory section 23doubling as output buffer means for temporarily storing the compressedvideo data reproduced by the disc unit section 28, thecompressing/expanding section 22 doubling as data expanding means forexpanding the compressed video data which has been read out from thebuffer memory section 23, and the SDI/F section 20 doubling as outputmeans for outputting data expanded by the compressing/expanding section22; and disc drive control section 5b for allowing the disc unit section28 to carry out, in a time-series manner, recording onto themagneto-optical disc of the compressed video data and reproduction fromthe magneto-optical disc, and controlling read-out timing of thecompressed video data from the buffer memory section 23 as the inputbuffer means, read-out timing of the compressed-video data from thebuffer memory section 23 as the output buffer means, and operation ofrecording/reproduction of the compressed video data by the disc unitsection 28 to allow the SDI/F section 20 to continuously output thecompressed video data therefrom.

Detailed configuration of the disc drive 5a will now be described.

Serial digital video data inputted from the SDI/F section 20 is suppliedto the compressing/expanding section 22 through a data formatter section21 for formatting the serial digital video data so as to become inconformity with processing within the disc drive 5a. Thecompressing/expanding section 22 compresses the video data suppliedthrough the data formatter section 21 to decrease quantity of datatransferred. It is conceivable that the compression processing at thistime is carried out in dependency upon intra-field or intra-framedifference, or inter-field or inter-frame difference of video data.Ordinarily, in the case where such a compression processing is carriedout, memory means such as frame memory or field memory are required. Inthis video data recording/reproducing unit, however, buffer memorysection 23 may be commonly used as the memory means. Compressed videodata which is output of the compressing/expanding section 22 is suppliedto a distributing/gathering section 24 through the buffer memory section23. This distributing/gathering section 24 distributes the compressedvideo data to the disc unit section 28 through error check codeadding/detecting section 25, buffer memory section 26 and protocolcontroller section 27 which will be described later.

While illustration is made in FIG. 3 such that disc unit section 28 iscomposed of magneto-optical disc units D1, D2 . . . D_(m-1), D_(m), thisinvention can be realized by using only one magneto-optical disc unitD1. In the case where the disc device section 28 is comprised of onlyone magneto-optical disc unit D1, the distributing/gathering section 24allows the compressed video data from the buffer memory section 23 to besimply passed therethrough to supply it to the error check codeadding/detecting section 25. Moreover, in the case where the disc unitsection 28 is composed of a plurality of magneto-optical disc units D1,D2 . . . D_(m-1), D_(m), the distributing/gathering section 24 dividesthe compressed video data from the buffer memory section 23 to supplythem to the error check code adding/detecting section 25.

The error check code adding/detecting section 25 adds codes for errorcorrection to the compressed video data. The protocol controller section27 is comprised of a Small Computer Systems Interface (hereinafterabbreviated as SCSI) protocol controller.

Detailed configuration of the disc drive control section 5b will now bedescribed.

At the disc drive control section 5b, control command supplied fromsystem control unit 9 through control system network 8 is taken thereinthrough network interface 31. The control command which has been takenin through the network interface 31 is decoded at Central ProcessingUnit (CPU) 34. As occasion demands, the control command is stored into aRandom Access Memory (RAM) 32. The control command which has beendecoded at CPU 34 is supplied to the disc drive 5a via interface 33 as acontrol signal. This disc drive control section 5b allows the disc unitsection 28 to carry out, in a time divisional manner, recording onto themagneto-optical of the compressed video data and reproduction from themagneto-optical disc, and controls read-out timing of the compressedvideo data from the buffer memory section 23 as the input buffer means,read-out timing of the compressed video data from buffer memory section23 serving as the output buffer means, and operation ofrecording/reproduction of the divided compressed video data by the discunit section 28 to allow the SDI/F section 20 to continuously output thevideo data therefrom.

The operation in the case where only one magneto-optical disc unit D1 ofthe disc unit section 28 is used will now be described.

In this example, data system network 10 for carrying out input/output ofvideo data between video data recording/reproducing unit 5 and datatransfer unit 6 within the server system 11 is caused to have differentlines with respect to input and output. It is to be noted that this datasystem network 10 can freely carry out switching between input andoutput.

The compressed video data which has been passed through thedistributing/gathering section 24 and has been caused to undergo aprocessing in which error check code is added thereto at the error checkcode adding/detecting section 25 is once (temporarily) written into abuffer memory 26₁. A protocol controller 27₁ records, onto themagneto-optical disc unit D1, the compressed video data which has beenread out from the buffer memory 26₁. Then, in a manner of time divisionwith respect to the recording operation, from the magneto-optical discunit D1, compressed video data for which request for reproduction isissued is read out through control of the protocol controller 27₁. Thecompressed video data thus read out is supplied to the error check codeadding/detecting section 28 through the buffer memory 26₁, at whicherror detection is carried out. The error detected compressed video datais passed through distributing/gathering section 24, and is written intoa buffer memory 23₂. This compressed video data is then read out fromthe buffer memory 23₂ at a predetermined timing. The data thus read outis expanded at a compressing/expanding circuit 22₂ so that data quantityis caused to be the same as that at the time when inputted to the SDI/Fcircuit 20₁. Then, the expanded video data is outputted from the datasystem network 10 to the data transfer unit 6 through a data formatter21₂ and a SDI/F circuit 20₂.

In the case of this example, in the magneto-optical disc unit D1 of thevideo data recording/reproducing unit 5, there is no necessity ofincluding a plurality of optical pick-up elements, but only one opticalpick-up is used to carry out, in a time divisional manner, operations ofrecording and reproduction, thus permitting input and output of videodata to be respectively continuously carried out without interruption interms of time when viewed from the external of the videorecording/reproducing unit 5. In addition, there is no necessity thatthis video data is the same video data file as video data outputtedthrough SDI/F circuit 20₂, but such video data may be different videodata file.

The video data inputted to the video data recording/reproducing unit 5through the data system network 10 from the data transfer unit 6 iscompressed by the compressing/expanding section 22, resulting in thecompressed video data. If compression factor at thecompressing/expanding section 22 is, e.g., 1/4, this video datarecording/reproducing unit 5 can handle video data of 4 channels at thesame time. For example, in the case where attention is drawn to the factthat only recording operation is carried out, when the compressionfactor is assumed to be 1/4, it is possible to record, in a timedivisional manner, four inputs.

Time-division recording of four inputs IN₁, IN₂, IN₃ and IN₄ will now bedescribed with reference to FIG. 4.

Initially, four inputs IN₁, IN₂, IN₃ and IN₄ as shown in FIG. 4 arestored into four buffer memories 23₁, 23₂, 23₃ and 23₄ through fourSDI/F 20₁, 20₂, 20₃ and 20₄, four data formatters 21₁, 21₂, 21₃ and 21₄,and four compressing/expanding circuits 22₁, 22₂, 22₃ and 22₄,respectively. These four inputs IN₁, IN₂, IN₃ and IN₄ are respectivelycompressed by compressing/expanding circuits 22₁, 22₂, 22₃ and 22₄,whereby video data of one frame, i.e., 1/30 seconds becomes compressedvideo data of 1/120 seconds as shown in FIG. 4. Thereafter, respectivecompressed video data are recorded in a time divisional manner in such amanner that it takes time of 1/120 seconds per one input at the singlemagneto-optical disc unit D1 through the error check codeadding/detecting section 25, the buffer memory 26₁, and the protocolcontroller 27₁. Accordingly, it takes 1/30 seconds (=1/120 seconds×4) intotal in order to carry out recording from input IN₁ up to input IN₄.For a time period during which such a recording processing is beingcarried out, video data of the subsequent one frame is sent in 1/30seconds to the compressing/expanding section 22. However, sincerecording processing of the above-mentioned four inputs IN₁, IN₂, IN₃and IN₄ is completed within 1/30 seconds, there is no possibility thatinput might be delayed. In this way, time-division recording of fourinputs IN₁, IN₂, IN₃ and IN₄ is carried out.

Moreover, this video data recording/reproducing unit 5 compresses thevideo data to carry out recording and reproduction in a time divisionalmanner, thereby making it possible to continuously carry out, withoutinterruption in point of time, both input of predetermined video dataand output of predetermined video data when viewed from the external ofthe video server system 11.

Time-division recording/reproduction relating to, e.g., two inputs andtwo outputs will now be described with reference to FIG. 5. It is to benoted that it is assumed that two inputs IN₁ and IN₂ are respectivelyinputted from SDI/F 20₁ and 20₂, and two outputs OUT₁ and OUT₂ arerespectively outputted from SDI/F 20₃ and 20₄. In addition, it isassumed that two inputs IN₁ and IN₂ from SDI/F 20₁ and 20₂ arerespectively processed every video data of one frame.

Initially, with respect to two inputs IN₁ and IN₂ as shown in FIG. 5,video data of one frame are stored into two buffer memories 23₁ and 23₂through SDI/F 20₁ and 20₂, data formatters 21₁ and 21₂, andcompressing/expanding circuits 22₁ and 22₂, respectively. These twoinputs IN₁ and IN₂ are respectively compressed by compressing/expandingcircuits 22₁, 22₂, whereby video data of one frame, i.e., 1/30 secondsbecomes compressed video data of 1/120 seconds as shown in FIG. 5.Thereafter, respective compressed data are recorded in a time divisionalmanner, in the state where it takes time of 1/120 seconds per one input,onto the single magneto-optical disc unit D1 through thedistributing/gathering section 24, the error check code adding/detectingsection 25, the buffer memory 26₁ and the protocol controller 27₁.

On the other hand, two outputs OUT₁ and OUT₂ are read out in atime-divisional manner by control of the protocol controller 27₁ fromthe single magneto-optical disc unit D1, and is supplied to the errorcheck code adding/detecting section 25 through buffer memory 26₁, atwhich error detection is made. The output OUT₁ is passed through thedistributing/gathering section 24 and is written into a buffer memory23₃. The output OUT2 is passed through the distributing/gatheringsection 24 and is written into a buffer memory 23₄. The time requireduntil output data are written into the buffer memories 23₃ and 23₄ is1/120 seconds per one output.

The compressed video data which have been written into the buffermemories 23₃ and 23₄ are respectively expanded at thecompressing/expanding circuits 22₃ and 22₄ so that compressed video dataof 1/120 seconds is converted into video data of 1/30 seconds. The videodata which have been expanded at the compressing/expanding circuits 22₃and 22₄ are outputted from the data system network 10 to the datatransfer unit 6 respectively through data formatters 21₃ and 21₄, andSDI/F circuits 20₃ and 20₄. The time required for this output is 1/30seconds which is the same as the times required for respective inputsIN₁, IN₂.

Accordingly, this video data recording/reproducing unit 5 compresses thevideo data to carry out recording and reproduction in a time divisionalmanner, thereby making it possible to continuously carry out, withoutinterruption in point of time, recording of predetermined video data andreproduction of predetermined video data when viewed from the externalof the video data recording/reproducing unit 5.

In FIG. 3, the SDI/F section 20 is composed of a plurality of SDI/Fcircuits 20₁, 20₂ . . . 20_(n). Moreover, data compressing/expandingsection 22 is composed of a plurality of compressing/expanding circuits22₁, 22₂ . . . 22_(n) for respectively compressing the video datainputted through the plurality of SDI/F circuits 20₁, 20₂ . . . 20_(n).Further, buffer memory section 23 serving as input buffer means iscomposed of a plurality of buffer memories 23₁, 23₂ . . . 23_(n) forrespectively storing the compressed video data compressed at theplurality of compressing/expanding circuits 22₁, 22₂ . . . 22_(n).Further, the disc unit section 28 is composed of a plurality ofmagneto-optical disc units D1, D2 . . . D_(m-1) and D_(m) forrecording/reproducing the compressed video data. In addition, the buffermemory section 23 serving as output buffer means is composed of aplurality of buffer memories 23₁, 23₂ . . . 23_(n) for respectivelytemporarily storing the video compressed data which have been read outat magneto-optical disc units D1, D2 . . . D_(m-1) and D_(m).

Moreover, the buffer memory section 26 is composed of a plurality ofbuffer memories 26₁, 26₂ . . . 26_(m-1), 28_(m). Further, the protocolcontroller section 27 is also composed of protocol controllers 27₁, 27₂. . . 27_(m-1) and 27_(m).

Furthermore, the distributing/gathering section 24 is connected betweena plurality of buffer memories 23₁, 23₂ . . . 23_(n) and a plurality ofmagneto-optical disc units D1, D2 . . . D_(m-1) and D_(m). By thedistributing/gathering section 24, the compressed video data suppliedfrom one of the plurality of buffer memories 23₁, 23₂ . . . 23_(n) maybe divided to distribute them to the plurality of magneto-optical discunits D1, D2 . . . D_(m-1) and D_(m). In addition, thedistributing/gathering section 24 may gather divided compressed videodata which have been respectively read out from the plurality ofmagneto-optical disc units D1, D2 . . . D_(m-1) and D_(m) to supplygathered data to any one of the plurality of buffer memories 23₁, 23₂ .. . and 23_(n).

Actually, the divided compressed video data which is output of thedistributing/gathering section 24 is supplied to the error check codeadding/detecting section 25, at which error check code is added thereto.Then, the error check code added divided compressed video data isrecorded onto magneto-optical disc units D1, D2 . . . D_(m-1) and D_(m)through buffer memories 26₁, 26₂ . . . 26_(m-1) and 26_(m), and protocolcontrollers 27₁, 27₂ . . . 27_(m-1) and 27_(m). Further, respectivedivided compressed video data which have been read out frommagneto-optical disc units D1, D2 . . . D_(m-1) and D_(m) and have beenreproduced through protocol controllers 27₁, 27₂, . . . 27_(m-1),27_(m), buffer memories 26₁, 26₂ . . . 26_(m-1) and 26_(m), and theerror check code adding/detecting section 25 are gathered at thedistributing/gathering section 24, and the data thus gathered issupplied to one of buffer memories which are not used for input of theplurality of buffer memories 23₁, 23₂ . . . 23_(n).

The compressed video data which has been read out from the one of buffermemories of the buffer memory sections 23 is expanded at correspondingone of compressing/expanding circuits 22₁, 22₂ . . . 22_(n), and issupplied to the data transfer unit 6 from the data system network 10through one of SDI/F circuits of the SDI/F section 20 which correspondto corresponding one of data formatters 21₁, 21₂ . . . 21_(n).

Accordingly, disc unit section 28 composed of a plurality ofmagneto-optical disc units D1, D2 . . . D_(m-1), D_(m) can carry out,continuously, in parallel, input and output of a greater number ofchannels with respect to processing time required for the input andprocessing time required for the output as compared to disc unit section28 comprised of only one magneto-optical disc unit D1. Moreover, thisvideo data recording/reproducing unit 5 can reproduce the portionrecorded, e.g., earlier by several minutes to several ten minutes withinthe same video data file without necessity of interruption of recordingof the entirety of the video data file. In addition, this video datarecording/reproducing unit 5 can supply the same video data file to aplurality of viewers with an arbitrary time difference.

While, in this embodiment, the disc unit section 28 is composed ofmagneto-optical disc units D1, D2 . . . D_(m-1) and D_(m), such discunit section may be random accessible recording/reproducing unit such ashard disc unit, etc.

Moreover, input channel and output channel composed of SDI/F section 20,compressing/expanding section 22, buffer memory section 23 and buffermemory section 26 may be used under the state where they arerespectively selectively exchanged each other.

Further, at least one of plural magneto-optical disc units D1, D2 . . .D_(m-1), D_(m) may be used to record/reproduce only the error checkcode.

Namely, this video data recording/reproducing unit 5 can increase thenumber of accessible inputs/outputs, and can immediately reproduce videodata being recorded at present or carry out, in parallel, withoutinterruption, both input of arbitrary video data and output of arbitraryvideo data.

A second embodiment of an information data processing system accordingto this invention will now be described below.

The configuration of the entirety of video data processing system 12which is the second embodiment is shown in FIG. 6. This video dataprocessing system 12 is provided, at the outside of a video datarecording/reproducing unit 18, with a data compressing unit forcompressing input video data from a video data input unit to obtaincompressed data, and/or a data expanding unit for expanding compresseddata read out from output buffer means. As the data compressing unit,there are compressing units 15 and 18, and compressing/expanding units13 and 17. Moreover, as the data expanding unit, there are expandingunit 14, and compressing/expanding units 13 and 17. In this embodiment,the compressing/expanding unit 13 is inserted in the middle of datatransfer system network 10 connecting data transfer unit 6 and editcontrol unit 7. Moreover, the expanding unit 14 is inserted in themiddle of the data transfer system network 10 connecting data transferunit 6 and signal sending-out unit 4. Further, compressing units 15 and16 are respectively inserted in the middle of data transfer systemnetworks 10 connecting data transfer unit 6 and receiving antenna 1 forcommunication satellite and connecting data transfer unit 6 andtelevision camera 2. In addition, compressing/expanding unit 17 isinserted in the middle of data transfer system network 10 connectingdata transfer unit 8 and video tape recorder 3.

The video data recording/reproducing unit 18 includes, as shown in FIGS.6 and 7, a disc drive 18a and a disc drive control section 18b. The discdrive control section 18b controls the operation of the disc drive 18aon the basis of a control signal supplied from system control unit 9.

Accordingly, outline of the configuration of the video data processingsystem 12 will be described below with reference to FIGS. 6 and 7.

The video data processing system 12 comprises, at the outside of thevideo data recording/reproducing unit 18, the video data input unit forgenerating video data such as video tape recorder 3, satellite antenna 1and television camera 2, video data output unit such as signalsending-out unit 4 and picture monitor unit, etc., compressing units 15and 16 and compressing/expanding units 13 and 17 which serve as a datacompressing unit for compressing the video data supplied from the videodata input unit to obtain compressed data, and expanding unit 14 andcompressing/expanding units 13 and 17 which serve as a data expandingunit for expanding the compressed data to supply it to the video dataoutput unit.

Moreover, the video data processing system 12 comprises, at the insideof the video data recording/reproducing unit 18, disc drive 18aincluding buffer memory section 23 serving as input buffer means fortemporarily storing the compressed data obtained by the data compressingunit, disc unit section 28 for recording the compressed data read outfrom the buffer memory section 23 onto a magneto-optical disc, andreproducing the compressed video data recorded on the magneto-opticaldisc, and buffer memory section 23 doubling as output buffer means fortemporarily storing the compressed video data reproduced by the discunit section 28; and disc drive control section 18b for allowing thedisc unit section 28 to carry out, in a time divisional manner,recording onto the magneto-optical disc of the compressed data andreproduction from the magneto-optical disc by the disc unit section 28,and controlling read-out timing of the compressed video data from thebuffer memory section 23 as the input buffer means, read-out timing ofthe compressed video data from the buffer memory section 23 as theoutput buffer means, and operations of recording/reproduction of thecompressed data by the disc unit section 28 to continuously output thecompressed video data from the buffer memory section 23.

Detailed configuration of the disc drive 18a will now be described withreference to FIG. 7.

Serial digital compressed video data inputted from SDI/F section 20 issupplied to buffer memory section 23 through data formatter section 21.The buffer memory section 23 temporarily stores the compressed videodata. The compressed video data which has been temporarily stored at thebuffer memory section 23 is supplied to the distributing/gatheringsection 24. This distributing/gathering section 24 distributes thecompressed video data through error check code adding/detecting section25, buffer memory section 28 and protocol controller section 27.

The distributing/gathering section 24 supplies the compressed video datato error check code adding/detecting section 25 for adding code forerror correction. The compressed video data to which error check codehas been added at the error check code adding/detecting section 25 issupplied to buffer memory section 26, and is written into the buffermemory section 26. The error check code added compressed video datawhich has been written into the buffer memory section 28 is recorded atthe disc unit section 28 through protocol controller section 27.

In this embodiment, SDI/F section 20, data formatter section 21, buffermemory section 23, buffer memory section 26, protocol controller section27, and disc unit section 28 have a plurality of circuits/units as shownin FIG. 7 similarly to corresponding respective portions within theabove-described video data recording/reproducing unit 5.

Accordingly, the distributing/gathering section 24 is connected betweena plurality of buffer memories 23₁, 23₂ . . . 23_(n) and a plurality ofmagneto-optical disc units D1, D2 . . . D_(m-1), D_(m), and distributesthe compressed video data supplied from one of the plural buffermemories 23₁, 23₂ . . . 23_(n) to the plural magneto-optical disc unitsD1, D2 . . . D_(m-1), D_(m) of the disc unit section 28. In addition,the distributing/gathering section 24 gathers, as described below,compressed video data which have been respectively read out from theplural magneto-optical disc units D1, D2 . . . D_(m-1), D_(m) to supplygathered data to any one of the plural buffer memories 23₁, 23₂ . . .23_(n).

While, in this embodiment, the disc unit section 28 is composed of aplurality of magneto-optical disc units D1, D2 . . . D_(m-1), D_(m),such section 28 may be composed of a plurality of hard discs.

Since detailed configuration of the disc drive control section 18b issimilar to that of the disc drive control section 5b shown in FIG. 2,the same reference numerals are respectively attached to correspondingportions, and their explanation is omitted.

In this embodiment, data system network 10 for carrying input/output ofvideo data between video data recording/reproducing unit 18 and datatransfer unit 6 within the video data processing system 12 havedifferent lines with respect to input and output. It is to be noted thatthe data system network 10 can freely carry out switching between inputand output.

The video data recording/reproducing unit 18 used in the video dataprocessing system 12 has no compressing means and expanding meanstherein. The compressing unit and the expanding unit exist outside thevideo data recording/reproducing unit 18. However, the video dataprocessing system 12 itself has a function to compress video data torecord it at the disc unit section 28 to expand reproduced compressedvideo data. For this reason, the video data processing system 12 cancarry out input and output operations as shown in the FIGS. 4 and 5mentioned above fundamentally as the entirety of the system.

Accordingly, this video data processing system 12 can respectivelycontinuously carry out input and output of a large number of video datawithout interruption in point of time when viewed from the external.

Namely, the video data processing system 12 of the second embodiment hasmerits similar to those of the first embodiment.

A further embodiment of the information data processing system accordingto this invention will now be described as a third embodiment. The thirdembodiment is Video On Demand (hereinafter abbreviated as VOD) usingvideo data recording/reproducing unit 8 which is the first embodiment.

This VOD system comprises, as shown in FIG. 8, a video library 32 inwhich a large number of video data files are stored, and a video server33 for supplying a large number of video data files from the videolibrary 32 to persons who makes a request for viewing and listeningthrough a signal transmission unit 34 by control of a system controller38.

Video data from a video software reproducing unit 30 for reproducingvideo media such as video tape or video disc, etc. is compressed at acompressing unit 31. The data thus compressed is then recorded onto amagneto-optical disc and is stored thereon at the video library 32.

The video server 33 further compresses video data file recorded on themagneto-optical disc of the video library 32 by using, e.g., video datarecording/reproducing unit 5 of the first embodiment to record them in atime divisional manner at the disc unit section 28. Then, the recordedcompressed video data is reproduced in a time divisional manner and isexpanded. The data thus reproduced and expanded is outputted to datatransfer unit (signal transmission unit) 34. Sincerecording/reproduction operation in a time divisional manner of thevideo server system 33 is similar to that of the video datarecording/reproducing unit 5 of the first embodiment, their explanationis omitted here.

The compressed video data supplied from the video server 33 is suppliedto an ATM switcher 38 through Asynchronous Transfer Mode (hereinafterabbreviated as ATM) interface 35₁ . . . 35_(n) constituting signalsending unit 34. Then, the compressed video data is supplied to DigitalNode Controller (hereinafter referred to as DNC) 37₁ . . . 37_(m)selected by the ATM switcher 38. Then, the compressed video data is sentto NODE receiving units 40₁ . . . 40_(m) through optical fiber cables39₁ . . . 39_(m). These NODE receiving units 40₁ . . . 40_(m) aredisposed with, e.g., user living areas being as units. For example,expanding units 41₁, 41₂, 41₃ . . . 41_(k) are connected to NODEreceiving unit 40₁. Moreover, expanding units 42₁, 42₂, 42₃, . . .42_(k) installed every users are connected to NODE receiving unit40_(m).

Request signal from user is supplied from an operation unit (not shown)installed on the user side along with expanding units 41₁, 41₂, 41₃ . .. 41_(k) to ATM switcher 36 through optical fiber cables 39₁ . . .39_(m) and DNCs 37₁ . . . 37_(m). The ATM switcher 36 supplies thisrequest signal to the system controller 38. The system controller 38decodes the request signal to control the video server 33 on the basisof the decoded result, and sends a message indicating that the requestsignal has been received to user through ATM switcher 36, etc.

The video server 33 takes video data file corresponding to a controlsignal from the system controller 38 into the disc unit section 28 bythe disc unit section 28 from the video library 32. Then, the videoserver 33 reproduces video data file corresponding to the controlsignal. The reproduced video data file is transmitted to the expandingunit of user through signal sending unit 34, optical fiber cables 39₁ .. . 39_(m), and NODE receiving units 40₁ . . . 40_(m).

Since the VOD system serving as the third embodiment uses theabove-mentioned video data recording/reproducing unit 5 in this way, itis possible to carry out, in a time divisional manner, recording andreproduction of a plurality of video data files.

Meanwhile, it is estimated that, in this VOD system, such a request toview video data file by variable speed, such as, for example, double ortriple speed may be issued from user. For this reason, in the VOD systemof the third embodiment, the disc unit section 28 of the video datarecording/reproducing unit 5 within the video server 33 is constructedas follows. It is to be noted that while video data file of one channelis assumed to be dealt for the brevity of explanation, it is easy toexpand the number of channels to plural channels.

In the case where the number of magneto-optical disc units constitutingthe disc unit section 28 is set to value except for multiple of 2 and 3,e.g., 7, video data divided in, e.g., frame units or field units aresequentially distributed to seven magneto-optical disc units D1, D2, D3,D4, D5, D6 and D7 and are recorded therein, and those video data arecaused to undergo n times speed reproduction, an approach is employed toreproduce, in parallel, video data of the n frame interval or n fieldinterval from the recording medium to transfer them to the buffer memoryto obtain video signals of frame or field of the n times speed from thebuffer memory.

When attention is drawn to one channel, sequential distributingrecording in this case is to divide video data in frame units todistribute divided data to seven magneto-optical disc units D1, D2, D3,D4, D5, D6 and D7 in the frame units to record them.

The state thereof will now be described with reference to FIG. 9. Inputvideo data divided in frame units are recorded in parallel in such amanner that frame F1 is recorded onto magneto-optical disc unit D1,frame F2 is recorded onto magneto-optical disc unit DE, and frame F3 isrecorded onto the magneto-optical unit D3. For this reason, input videodata are recorded at 7 frame intervals in a manner of frame F1, frameF8, frame F15 . . . onto, e.g., magneto-optical disc unit D1.

Reproduction by various speeds of the disc unit section 28 in the casewhere input video data are being caused to undergo distributingsequential recording in frame units in this way will now be describedbelow.

Initially, standard reproduction will now be described with reference toFIG. 9.

In this case, the protocol controller 27 reads, from magneto-opticaldisc unit D1˜magneto-optical disc unit D7, by control of the disc drivecontrol section 5b, video data of frame unit of frame F1 up to frame F7recorded on magneto-optical disc units D1˜D7 to store them intopredetermined areas A1˜A7 of the buffer memory 28. When taking in ofdata has been completed, the buffer memory 28 sends out video data offrame F1˜frame F7 to the error check code adding/detecting section 25.For this time period, video data of frame F8 up to frame F14 recorded onmagneto-optical disc unit D1˜magneto-optical disc unit D7 are storedinto the buffer memory section 26. Then, such an operation isalternately repeated. Thus, video data of frame unit recorded on thedisc unit section 28 are sequentially subjected to standardreproduction.

Double speed reproduction will now be described with reference to FIG.10.

In this case, the protocol controller 27 reads, from the magneto-opticaldisc units D1˜D7, by control of the disc drive control section 5b, videodata of frame unit of frame F8 recorded on magneto-optical disc unit D1,frame F2 recorded on magneto-optical disc unit D2, frame F10 recorded onmagneto-optical disc unit D3, frame F4 recorded on magneto-optical discunit D4, frame F12 recorded on magneto-optical disc unit D5, frame F6recorded on magneto-optical disc unit D6, and frame F14 recorded onmagneto-optical disc unit D7 to store those video data intopredetermined areas A1˜A7 of the buffer memory 26. When taking-in ofdata has been completed, the buffer memory 26 sends out, to the errorcheck code adding/detecting section 25, the frame F2, the frame F4, theframe F6, the frame F8 and the frame F14 which have been selectivelysubjected to sequencing. For this time period, video data of frame F22recorded on magneto-optical disc unit D1, frame F16 recorded onmagneto-optical disc unit D2, frame F24 recorded on magneto-optical discunit D3, frame F18 recorded on magneto-optical disc unit D4, frame F28recorded on magneto-optical disc unit D5, frame F20 recorded onmagneto-optical disc unit D6, and frame F28 recorded on magneto-opticaldisc unit D7 are stored into the buffer memory 26. After respective dataare selectively subjected to sequencing, they are sent out to the errorcheck code adding/detecting section 25 in order of frame F18, frame F18,frame F20, frame F22, frame F24, frame F28 and frame F28. By alternatelyrepeating such an operation, video data of frame unit recorded at thedisc unit section 28 are sequentially subjected to double speedreproduction.

Triple speed reproduction will now be described with reference to FIG.11.

In this case, the protocol controller 27 reads, from magneto-opticaldisc units D1˜D7, by control of the disc drive control section 5b, videodata of frame unit of frame F15 recorded on magneto-optical disc unitD1, frame F9 recorded on magneto-optical disc unit D2, frame F3 recordedon magneto-optical disc unit D3, frame F18 recorded on magneto-opticaldisc unit D4, frame F12 recorded on magneto-optical disc unit D5, frameF6 recorded on magneto-optical disc unit D6, and frame F21 recorded onmagneto-optical disc unit D7 to store those data into predeterminedareas A1˜A7 of the buffer memory 26. When taking-in of data has beencompleted, the buffer memory 26 sends out, to the error check codeadding/detecting section 25, the frame F3, the frame F6, the frame F9,the frame F12, the frame F15, the frame F18 and the frame F21 which havebeen selectively subjected to sequencing. For this time period, frameF36 recorded on magneto-optical disc unit D1, frame F30 recorded onmagneto-optical disc unit D2, frame F24 recorded on magneto-optical discunit D3, frame F39 recorded on magneto-optical disc unit D4, frame F33recorded on magneto-optical disc unit D5, frame F27 recorded onmagneto-optical disc unit D6, and frame F42 recorded on magneto-opticaldisc unit D7 are stored into the buffer memory 26. Then, after thosedata are selectively subjected to sequencing, they are sent out to theerror check code adding/detecting section 25 in order of frame F24,frame F27, frame F30, frame F33, frame F36, frame F39, and frame F42. Byalternately repeating such an operation, video data of frame unitrecorded at the disc unit section 28 are sequentially subjected totriple (three times) speed reproduction.

As stated above, the VOD system which is the third embodiment employs ascheme to allow the number of magneto-optical disc units constitutingthe disc unit section to be set to 7 except for multiple of 2 and 3 tosequentially distribute video signals divided in frame units to sevenmagneto-optical disc units to record those signals therein, wherein inthe case where these video signals are subjected to n times speedreproduction, video signals of the n frame interval are caused toundergo parallel reproduction through the protocol controller 27 fromrespective disc units D1˜D7 of the disc unit section 28 to transferreproduced data to the buffer memory 26 to send out a video signal offrame of n times speed from the buffer memory 28 to the error check codeadding/detecting section 25, thus making it possible to efficientlycarry out double speed reproduction or fast feed.

It should be noted that since the number of magneto-optical disc unitsof the disc unit section 28 is 7, it is impossible to carry out variablespeed reproduction of multiple of 7 like 7 times speed or 14 timesspeed.

The VOD system may be of a structure in which, e.g., the disc drivesection is composed of five magneto-optical disc units. In this case, itis possible to realize reproduction of double speed, triple speed andfour times speed. Namely, it is sufficient to select, in dependency uponthe specification required, the number of installation of disc units ofthe disc unit section so that it is equal to value except for multipleof 2 and 3, numbers except for multiple of 2 and except for multiple of3, e.g., 5, 7, 11, 13, 17, 19 . . . in a practical sense.

Moreover, while, in the case of triple speed reproduction, for example,reproduction is made in order of frame F3, frame F6, frame F9, frame F12. . . , reproduction may be made in order of frame F2, frame F5, frameF8, frame F11 . . . This similarly applies to the case of double speedreproduction, four times speed reproduction, and five times speedreproduction. In addition, the disc unit constituting the disc unitsection is not limited only to the magneto-optical disc unit, but may behard disc unit.

Further, also with respect to video data recording/reproducing units 18and 5 used in the video data processing system of the second embodimentand the VOD system of the third embodiment, at least one of pluralmagneto-optical disc units may be used for recording/reproduction of theerror correction code.

Furthermore, video server system 11 including video datarecording/reproducing unit 5 of the first embodiment, the video datainput unit and the video data output unit may be used to constitute avideo data processing system.

In addition, while video data file of one channel is assumed to behandled in the explanation of the variable speed reproduction processingof the VOD system of the third embodiment, the number of channels to behandled may be expanded to plural channels.

What is claimed is:
 1. Apparatus for recording and reproducinginformation data to and from a recording medium, comprising:input meansfor supplying said information data; data compressing means forcompressing said information data to generate compressed data; inputbuffer means for temporarily storing the compressed data;recording/reproducing means for recording the compressed data read outfrom the input buffer means onto a recording medium in a time divisionalmanner, and reproducing the compressed data recorded on the recordingmedium in a time divisional manner; output buffer means for temporarilystoring the compressed data reproduced by the recording/reproducingmeans; data expanding means for expanding the compressed data read outfrom the output buffer means; output means for outputting the dataexpanded by the expanding means; and control means for controllingread-out timing of the compressed data from the input buffer means andread-out timing of the compressed data from the output buffer means suchthat said recording/reproducing means continuously records andreproduces the information data to and from the recording mediumsimultaneously.
 2. The apparatus as set forth in claim 1, furthercomprising dividing means for dividing the compressed data into multipleunits of the compressed data; and wherein said recording/reproducingmeans includes a plurality of recording circuits, each recording andreproducing a respective unit of the compressed data.
 3. The apparatusas set forth in claim 2, further comprising error correction code addingmeans for adding error correction code to the compressed data, andwherein at least one of the plurality of recording/reproducing circuitsrecords and reproduces only the error correction code.
 4. The apparatusas set forth in claim 1, whereinthe input means includes a plurality ofinterface circuits, the data compressing means includes a plurality ofcompressing circuits for respectively compressing the information datafrom the plurality of interface circuits; the input buffer meansincludes a plurality of input buffer circuits for respectively storingthe compressed data compressed by the plurality of compressing circuits;the recording/reproducing means includes a plurality ofrecording/reproducing circuits for recording and reproducing thecompressed data; and the output buffer means includes a plurality ofoutput buffer circuits for respectively temporarily storing thecompressed data reproduced by the plurality of recording/reproducingcircuits, and the apparatus further comprises distributing/gatheringmeans connected to the plurality of input buffer circuits, the pluralityof output buffer circuits and the plurality of recording/reproducingcircuits for dividing the compressed data from one of the plurality ofinput buffer circuits into a plurality of units of compressed data,supplying the plurality of units of compressed data to the plurality ofrecording/reproducing circuits, and combining compressed datarespectively reproduced from the plurality of recording/reproducingcircuits to supply the combined compressed data to one of the pluralityof output buffer circuits.
 5. The apparatus as set forth in claim 2,wherein each recording/reproducing circuit is a disc unit adapted forrecording the compressed data onto a disc shaped recording medium, andreproducing the compressed data from the disc-shaped recording medium.6. The apparatus as set forth in claim 1, wherein the input means andthe output means, the data compressing means and the data expandingmeans, and the input buffer means and the output buffer means can beused so that they are respectively selectively replace each other.
 7. Asystem for processing information data, comprising:at least one inputunit for generating information data; at least one output unit foroutputting information data; and an information datarecording/reproducing unit comprising data compressing means forcompressing the information data supplied from the information datainput unit to obtain compressed data, input buffer means for temporarilystoring the compressed data obtained by the data compressing means,recording/reproducing means for recording the compressed data read outfrom the input buffer means onto a recording medium in a time divisionalmanner and reproducing the compressed data recorded on the recordingmedium in a time divisional manner, output buffer means for temporarilystoring the compressed data reproduced by the recording/reproducingmeans, data expanding means for expanding the compressed data read outfrom the output buffer means, and control means for controlling read-outtiming of the compressed data from the input buffer means and readouttiming of the compressed data from the output buffer such that saidrecording/reproducing means continuously records and reproduces theinformation data to and from the recording medium simultaneously.
 8. Asystem for processing information data, comprising:at least one inputunit for generating information data; a data compressing unit forcompressing the information data to generate compressed data; aninformation data recording/reproducing unit comprising input buffermeans for temporarily storing the compressed data, recording/reproducingmeans for recording the compressed data read out from the input buffermeans onto a recording medium in a time divisional manner andreproducing the compressed data recorded on the recording medium in atime divisional manner, output buffer means for temporarily storing thecompressed data reproduced by the recording/reproducing means, andcontrol means for controlling read-out timing of the compressed datafrom the input buffer means and read-out timing of the compressed datafrom the output buffer means such that said recording/reproducing meanscontinuously records and reproduces the information data to and from therecording medium simultaneously; a data expanding unit for expanding thecompressed data outputted from the information datarecording/reproducing unit; and an output unit for outputting dataexpanded by the data expanding unit.
 9. The system as set forth in claim8, wherein the recording/reproducing means further includes dividingmeans for dividing the compressed data into multiple units of thecompressed data and a plurality of recording/reproducing circuits, eachrecording and reproducing a respective unit of the compressed data. 10.The system as set forth in claim 9, wherein the information datarecording/reproducing unit further includes error correction code addingmeans for adding error correction code to the compressed data, and atleast one of the plurality of recording/reproducing circuits isoperative to record and reproduce only the error correction code. 11.The system as set forth in claim 8,wherein the data compressing unitincludes a plurality of compressing circuits; the input buffer meansincludes a plurality of input buffer circuits for respectively storingthe compressed data compressed by the plurality of compressing circuits;the recording/reproducing means includes a plurality ofrecording/reproducing circuits for recording and reproducing thecompressed data; and the output buffer means includes a plurality ofoutput buffer circuits for respectively temporarily storing thecompressed data reproduced at the plurality of recording/reproducingcircuits, and further comprising distributing/gathering means connectedto the plurality of input buffer circuits, the plurality of outputbuffer circuits, and the plurality of recording/reproducing circuits fordividing the compressed data from one of the plurality of input buffercircuits into multiple units of the compressed data, supplying themultiple units of compressed data to the plurality ofrecording/reproducing circuits, and combining compressed datarespectively reproduced from the plurality of recording/reproducingcircuits to supply the combined compressed data to one of the pluralityof output buffer circuits.
 12. The system as set forth in claim 8,wherein the input buffer means and the output buffer means can be usedinterchangeably.
 13. The system as set forth in claim 8, wherein therecording/reproducing means includes plural number (except for multipleof 2 and 3) of recording/reproducing circuits; wherein said dividingmeans is operable to divide the compressed data into frame or fieldunits; wherein the plurality of recording/reproducing circuitssequentially record said frame or field units of the compressed data;and wherein the plurality of units or n field units of the compresseddata from the recording medium to provide reproduction at n times normalspeed, where n is an integer.
 14. The system as set forth in claim 9,wherein each recording/reproducing circuit is a disc unit adapted forrecording the compressed data onto a disc-shaped recording medium, andreproducing the compressed data from the disc-shaped recording medium.